The rockefeller university

Event Details

Type

Center for Studies in Physics and Biology Seminars

Speaker(s)

Deepak Krishnamurthy, Ph.D., 2024 BWF CASI Fellow, University of California, Berkeley

Speaker bio(s)

Our oceans make up 90% of the planet's biosphere. Yet, paradoxically, this vast ecosystem is built from the bottom up, with single cells driving its most critical processes. Microbial phytoplankton alone generate 50% of Earth's oxygen and fix half of all carbon, matching the impact of terrestrial life. In the sunlit upper ocean, single-cell biomass and planktonic products aggregate and sink as "marine snow," powering the "biological carbon pump," one of Earth's largest carbon fluxes estimated at 5-12 GtC per year. Mechanistically unraveling this pump demands connecting microscale cellular processes to ecological-scale phenomena - a challenge requiring new biophysical approaches. In the first part of my talk, I'll present our development of scale-free vertical tracking microscopy - a new system for measuring single cells, marine larvae, and sinking aggregates with microscopic resolution across ecologically relevant depths of tens to hundreds of meters. I'll share vignettes of discoveries enabled by this tool, including novel cell motility in diatoms, behavioral repertoires of key marine larvae in "virtual-reality" environments, and the impact of single-cell processes on flow and mass transport to sinking aggregates. In the second part, I'll discuss ongoing work using choanoflagellates as a model for the biophysics of cell adhesion and behavior in the ocean. Protists - a remarkably diverse class of unicellular eukaryotes, including choanoflagellates - constitute 2 GtC of marine biomass, equal to all marine animals. Yet their ecosystem roles are just starting to be uncovered. I focus on loricate choanoflagellates: single cells that rapidly (in minutes) build intricate, silicaceous "lorica" baskets from hundreds of rod-like costal strips (2-3 µm long, 100 nm wide). I'll explore how these cells modulate surface adhesion interactions in space and time, emphasizing the role of glycans, charge, and biophysical surface properties. Loricate choanoflagellates offer a powerful model to probe the limits of single cell behavior, microscale biological self-assembly, and modulation of adhesive interactions in the marine environment. I'll close with future directions: developing high-throughput assays at both molecular and cellular scales to measure adhesion interactions between cells and between cells and surfaces, with applications to marine snow formation and its emergent biophysical properties. These approaches are critical for biophysically constraining carbon flux models, elucidating the nonlinear microscale interactions that cause flux attenuation with depth, and predicting how the biological carbon pump will respond to anthropogenic stressors.

Open to

Public

Phone

(212) 327-8636

Sponsor

Melanie Lee
(212) 327-8636
leem@rockefeller.edu